Administration apparatus for medical use

ABSTRACT

An expansion/compression mechanism of a piston rod assembly is composed of a bush shaft, a first cylindrical piston rod that is screwed with the bush shaft, a second cylindrical piston rod that is screwed with the first piston rod, and a piston rod holding member for housing the bush shaft and these piston rods. Therefore, the piston rods move linearly in multiple stages.

This application is a divisional of application Ser. No. 12/248,282,filed Oct. 10, 2008, which is a divisional application Ser. No.11/071,466, filed Mar. 4, 2005, now abandoned.

FIELD OF THE INVENTION

The present invention relates to an administration apparatus for medicaluse which is driven by an electric driving source to performadministration of a drug and, more particularly, to an administrationapparatus that facilitates replacement of drug cartridges.

BACKGROUND OF THE INVENTION

A patient addicted to insulin must get plural injections of insulin perweek or day. A required amount of insulin varies from patient topatient. A required amount of insulin for each patient varies frominjection to injection, and it also varies from day to day.

A patient who performs injection by himself attaches a drug cartridgecontaining a drug to an injector, and attaches a needle assembly to anelastic seal of the drug cartridge, and thereafter, sets a dose, andoperates the injector to inject the drug into his body. The drug in thedrug cartridge runs out when such administration is performed a fewtimes. The patient detaches an empty drug cartridge from the injector,and attaches a new drug cartridge to repeat the above-mentionedinjection. As for a conventional injector, when the drug cartridge isreplaced with a new cartridge, a member that holds the drug cartridge(hereinafter referred to as a cartridge holder) is detached from a bodyof the injector, and the drug cartridge is detached from the cartridgeholder. Then, a new drug cartridge is inserted into the cartridgeholder, and thereafter, the cartridge holder is attached to the injector(for example, see Japanese Utility Model Registration No. 3088706).

Although the above-mentioned conventional injector is a hand-operatedinjector, there is a motor-operated injector as shown in FIG. 24. FIG.24 is a diagram illustrating inner structure of a motor-operatedinjector which is currently popular for dental use. A principle of drugadministration will be described with reference to FIG. 24. A syringe203 filled with a drug is set in a cartridge holder 202 attached to abody 210.

When a switch SW1 is pressed, a motor 211 rotates forward, and arotational force is decelerated by a deceleration gear box 209 that isdirectly connected to the motor 211, whereby a deceleration gear mainshaft 208 of the deceleration gear box 209 is rotated. An end of thedeceleration gear main shaft 208 is engaged with a gear 206 via arotation plank 207, whereby the gear 206 is rotated. Further, since thegear 206 is engaged with a gear 205, a rotational force of the gear 206propagates to the gear 205. A gear 205 a is located coaxially with thegear 205 so as to be engaged with a rack 204 a that is provided on alower right half of an extrusion piston 204. When the gear 205 rotates,the gear 205 a also rotates in the same direction as the gear 205, andconsequently, the extrusion piston 204 moves toward an injection needle213, whereby drug in the syringe 203 is pressed out of the injectionneedle 213.

During injection, after performing air releasing in the above-mentionedoperation, the injection needle 213 is inserted into a target area, andthe drug is administered. In FIG. 24, SW2 denotes a switch for rotatingthe motor 211 in a reverse order, and 212 denotes a battery for drivingthe motor 211.

Further, it is very important for an insulin injector to be portable,and therefore, a compact and light-weight injector is desired. Theconventional injector is generally provided with a linear piston havinga stroke that enables injection of all drug in the drug cartridge.However, there is an injector provided with a curvature type piston (forexample, see Japanese Published Patent Application No. 2000-513974).

By the way, when a patient actually uses an injector, the patientdesires easy replacement of drug cartridges.

In the conventional injector, however, the patient must detach thecartridge holder into which the drug cartridge is inserted from the bodyof the injector, detach the drug cartridge from the cartridge holder,attach a new drug cartridge to the holder, and mount the cartridgeholder onto the injector body, resulting in an inconvenient andtroublesome operation.

Further, in a case of the injector having a linear piston, the pistonmust have a stroke that enables injection of all drug in the drugcartridge, and a length of the piston becomes approximately equal to anentire length of the drug cartridge. Therefore, a length of the injectoritself becomes at least two times as long as the drug cartridge, leadingto an increase in a size of the injector. Further, in a case of theinjector having a curvature type piston, a length of the injectorbecomes shorter than that of the linear piston rod. However, since thepiston has a curvature, a thickness of the injector is increased,leading to a disadvantage in handleability.

Furthermore, in the conventional administration apparatus for medicaluse shown in FIG. 24, although operation is easy because drug injectionis motor-operated, the patient might be anxious as to whether or not themotor-operated injector including a drive mechanism such as a motor isnormally operated. An act of drug administration itself provides mentalstress to the patient, and furthermore, abnormal operation of themotor-operated injector greatly affects a human body, which may endangerthe life of the patient.

The conventional administration apparatus for medical use is constructedas described above, and operation of cartridge replacement istroublesome.

Further, a size of the apparatus is too large to handle.

Furthermore, as for the motor-operated apparatus, the patient might beanxious during drug administration about air releasing before injection,an operation state of a mechanism, or the like.

SUMMARY OF THE INVENTION

The present invention is made to solve the above-described problems andhas for its object to provide an administration apparatus for medicaluse which enables a patient to easily replace cartridges, and minimizesa size of an injector itself.

It is another object of the present invention to provide anadministration apparatus for medical use which eases physical and mentalpains of a patient by detecting abnormal operation during injection andinforming the same to a patient, thereby enabling the patient to performadministration of a drug with high stability.

Other objects and advantages of the invention will become apparent froma detailed description that follows. The detailed description andspecific embodiments described are provided only for illustration sincevarious additions and modifications within the scope of the inventionwill be apparent to those of skill in the art from the detaileddescription.

According to a first aspect of the present invention, an administrationapparatus for medical use includes: a drug cartridge having an endclosed with a plunger, and containing a drug inside; a cartridge holderfor holding the drug cartridge; a needle holder which is provided at anend of the cartridge holder slidably in an axial direction of thecartridge holder, and is swingable with respect to the axial directionat its sliding end portion; and a needle assembly for inserting a needleinto a target region, and administrating the drug that is ejected fromanother end of the drug cartridge by movement of a piston rod thatpresses the plunger in the drug cartridge, with the needle assemblybeing detachably provided on the needle holder, wherein the needleholder is slid in the axial direction of the cartridge holder as well asbeing swung with respect to the axial direction at its sliding endportion, thereby exposing a front end portion of the drug cartridge at afront end of the cartridge holder to detach the drug cartridge from thecartridge holder. Therefore, the drug cartridge can be detached orattached from/to the cartridge holder with the cartridge holder beingheld by the administration apparatus, thereby facilitating cartridgereplacement.

According to a second aspect of the present invention, in theadministration apparatus for medical use according to the first aspect,detaching of the drug cartridge is possible in a state where the needleassembly is attached to the needle holder. Therefore, handling isfacilitated.

According to a third aspect of the present invention, in theadministration apparatus for medical use according to the first aspect,the needle holder is provided with a lever for moving the drug cartridgetoward the piston rod with an operation of attaching the needle assemblyto the needle holder. Therefore, it is possible to check whether or notthe needle assembly is attached by detecting a state of the lever.

According to a fourth aspect of the present invention, in theadministration apparatus for medical use according to the first aspect,the cartridge holder is provided with a force-applying member forpushing the drug cartridge toward the needle holder. Therefore, it ispossible to check whether or not the needle assembly and the drugcartridge are attached by detecting a position of a force-applying unitattached to the cartridge holder.

According to a fifth aspect of the present invention, in theadministration apparatus for medical use according to the first aspect,when replacing the drug cartridge, the piston rod is moved back to itsinitial position with an operation of moving the needle holder toward aposition where the needle assembly is attached. Therefore, the pistonrod can be returned to the initial position when replacing thecartridge, leading to improved operability.

According to a sixth aspect of the present invention, the administrationapparatus for medical use according to the first aspect further includesa movable target-region contact cover that covers a peripheral sidesurface of the needle holder, and only a needle of the needle assemblyis exposed from the target-region contact cover when performinginjection. Therefore, a periphery of the needle holder is covered withthe target-region contact cover except when performing injection,thereby preventing a danger such that the needle is inserted by mistake.

According to a seventh aspect of the present invention, in theadministration apparatus for medical use according to the sixth aspect,when replacing the drug cartridge, the target-region contact cover ismoved to a position where the needle holder is exposed. Therefore, auser can easily touch the needle holder when replacing the drugcartridge, leading to improved operability.

According to an eighth aspect of the present invention, theadministration apparatus for medical use according to the sixth aspectfurther includes a unit for detecting a position of the target-regioncontact cover. Therefore, an accident such that the needle is insertedby mistake during use can be effectively avoided.

According to a ninth aspect of the present invention, an administrationapparatus for medical use includes: a drug cartridge having an endclosed with a plunger, and containing a drug inside; a cartridge holderfor holding the drug cartridge; and a piston rod assembly having pluralstages of expansion/compression mechanisms, and pushing the plunger inthe drug cartridge to move the plunger. Since motion of the piston rodis linear in plural stages, a size of the apparatus is significantlyreduced, thereby providing an administration apparatus for medical usehaving excellent portability.

According to a tenth aspect of the present invention, in theadministration apparatus for medical use according to the ninth aspect,the plural stages of expansion/compression mechanisms of the piston rodassembly have plural stages of piston rods which are linearly slidablein parallel to an axial direction of the cartridge holder, and a lengthof each piston rod is shorter than an entire length of the drugcartridge. Since motions of the piston rods are linear in plural stages,a size of the apparatus is significantly reduced, thereby providing anadministration apparatus for medical use having excellent portability.

According to an eleventh aspect of the present invention, in theadministration apparatus for medical use according to the tenth aspect,the plural piston rods are concentrically arranged, and the piston rodsare successively slid from a piston rod that is positioned at anoutermost concentric circle. Since motions of the piston rods are linearin plural stages, a size of the apparatus is significantly reduced,thereby providing an administration apparatus for medical use havingexcellent portability.

According to a twelfth aspect of the present invention, anadministration apparatus for medical use which performs administrationof a drug using an electric driving source, comprises: a drug cartridgehaving an end closed with a plunger, and containing a drug inside; acartridge holder for holding the drug cartridge; a piston rod forpressing the plunger held in the drug cartridge to move the plunger; aneedle assembly for inserting a needle into a target region, andadministering the drug that is emitted from another end of the drugcartridge with movement of the piston rod; and a control circuit forcontrolling an air releasing operation for the drug cartridge and/or theinjection needle so that the air releasing operation is performed at aspeed lower than a speed of drug administration. Therefore, it ispossible to reduce a risk of the drug adhered to the injection needle orthe like being splattered when a user visually checks air releasing, andreduce mental pain due to administration.

According to a thirteenth aspect of the present invention, in theadministration apparatus for medical use according to the twelfthaspect, the air releasing operation is performed with movement of thepiston rod. Therefore, the air releasing operation is facilitated.

According to a fourteenth aspect of the present invention, in theadministration apparatus for medical use according to the thirteenthaspect, during the air releasing operation, the piston rod is moved at aspeed lower than a speed of the piston rod during drug administration.Therefore, it is possible to reduce a risk of the drug adhered to theinjection needle or the like being splattered when the user visuallychecks air releasing, and reduce mental pain due to administration.

According to a fifteenth aspect of the present invention, in theadministration apparatus for medical use according to the fourteenthaspect, such low-speed operation of the piston rod during the airreleasing operation is performed by PWM (Pulse Width Modulation) controlfor controlling the piston rod with an ON-OFF ratio of a pulse widthbeing varied. Therefore, it is possible to reduce a risk of the drugadhered to the injection needle or the like being splattered when theuser visually checks air releasing, and reduce mental pain due toadministration.

According to a sixteenth aspect of the present invention, in theadministration apparatus for medical use according to the fourteenthaspect, such low-speed operation of the piston rod during the airreleasing operation is performed by voltage control. Therefore, it ispossible to reduce a risk of the drug adhered to the injection needle orthe like being splattered when the user visually checks air releasing,and reduce mental pain due to administration.

According to a seventeenth aspect of the present invention, anadministration apparatus for medical use which performs administrationof a drug using an electric driving source, comprises: a drug cartridgehaving an end closed with a plunger, and containing a drug inside; acartridge holder for holding the drug cartridge; a piston rod forpressing the plunger in the drug cartridge to move the plunger; a needleassembly for inserting a needle into a target region, and administeringthe drug that is emitted from another end of the drug cartridge withmovement of the piston rod; and a control circuit for performing controlso that an air releasing operation for the drug cartridge and/or theinjection needle is always performed before performing a drugadministration operation. Therefore, air releasing is always performedbefore drug administration, whereby mental anxiety to a user can bereduced.

According to an eighteenth aspect of the present invention, theadministration apparatus for medical use according to the seventeenthaspect further includes an air releasing switch for performing the airreleasing operation, and an administration switch for injecting thedrug, and the control circuit permits an operation by turn-on of theadministration switch after the air releasing operation. Therefore,there is no fear of drug administration when air releasing is notperformed, whereby mental anxiety to a user can be reduced.

According to a nineteenth aspect of the present invention, theadministration apparatus for medical use according to the twelfth orseventeenth aspect further includes a contact sensor for detectingwhether or not a portion of the administration apparatus in the vicinityof the needle assembly contacts a target region, and the air releasingoperation is suppressed when the contact sensor contacts the targetregion. Therefore, it is possible to prevent an accident such that theneedle is inserted into the human body during air releasing, wherebymental anxiety to the user can be reduced.

According to a twentieth aspect of the present invention, anadministration apparatus for medical use which performs administrationof a drug using an electric driving source, comprises: a drug cartridgehaving an end closed with a plunger, and containing a drug inside; acartridge holder for holding the drug cartridge; a piston rod forpressing the plunger in the drug cartridge to move the plunger; a needleassembly for inserting a needle into a target region, and administeringthe drug that is emitted from another end of the drug cartridge withmovement of the piston rod; a dose setting circuit for setting, by auser, a dose of drug to be administered; a dose holding circuit forholding doses of drug which have been administered in the past; a dosecomparison circuit for comparing a dose that is set by the dose settingcircuit with doses that are held in the dose holding circuit; and acontrol circuit for performing control so as to suppress operation ofthe piston rod when a result of this comparison by the dose comparisoncircuit is equal to or larger than a predetermined value. Therefore, theuser cannot proceed to an administration step when the dose changessignificantly, thereby reducing mental and physical pains caused by useof the motor-operated administration apparatus for medical use.

According to a twenty-first aspect of the present invention, in theadministration apparatus for medical use according to the twentiethaspect, the dose holding circuit holds a dose of drug that has beenadministered most recently, and the dose comparison circuit compares adose that is set by the user with the dose that has been administeredmost recently. Therefore, the user cannot proceed to the administrationstep when the dose changes significantly, thereby reducing mental andphysical pains caused by use of the motor-operated administrationapparatus for medical use.

According to a twenty-second aspect of the present invention, in theadministration apparatus for medical use according to the twentiethaspect, the dose holding circuit holds doses of drug of plural times ofadministrations performed in the past, and the dose comparison circuitcompares a dose that is set by the user with a dose that is obtained onbasis of the plural times of administrations performed in the past.Therefore, the user cannot proceed to the administration step when thedose changes significantly, thereby reducing mental and physical painscaused by use of the motor-operated administration apparatus for medicaluse.

According to a twenty-third aspect of the present invention, in theadministration apparatus for medical use according to the twenty-secondaspect, the dose obtained on the basis of the plural times ofadministrations performed in the past is an average of doses of theplural times of administrations in the past. Therefore, the user cannotproceed to the administration step when the dose changes significantly,thereby reducing mental and physical pains caused by use of themotor-operated administration apparatus for medical use.

According to a twenty-fourth aspect of the present invention, theadministration apparatus for medical use according to the twentiethaspect further includes a notification unit for notifying the user thatadministration is not possible, when the result of comparison by thedose comparison circuit is equal to or larger than the predeterminedvalue. When the dose changes significantly, it is informed to the userand then the user confirms the dose, thereby reducing mental andphysical pains caused by use of the motor-operated administrationapparatus for medical use.

According to a twenty-fifth aspect of the present invention, in theadministration apparatus for medical use according to the twenty-fourthaspect, when the user permits administration of the dose of drug that isset by the user after the user is notified that administration is notpossible using the notification unit, the control circuit cancelsrestriction on operation of the piston rod. Therefore, even when thedose changes significantly, the user can perform administration for hisown convenience. Since this dose change is informed to the user beforeadministration and then the user can check the dose, mental and physicalpains caused by use of the motor-operated administration apparatus formedical use can be reduced.

According to a twenty-sixth aspect of the present invention, anadministration apparatus for medical use which performs administrationof a drug using an electric driving source, comprises: a drug cartridgehaving an end closed with a plunger, and containing a drug inside; acartridge holder for holding the drug cartridge; a piston rod forpressing the plunger held in the drug cartridge to move the plunger; aneedle assembly for inserting a needle into a target region, andadministering the drug that is emitted from another end of the drugcartridge with movement of the piston rod; a dose setting circuit forsetting, by a user, a dose of drug to be administered; a dose detectioncircuit for detecting an actual dose of drug using an electroniccircuit; and a comparison detection circuit for comparing a dose that isset by the dose setting circuit with a result of detection by the dosedetection circuit to detect overdose or underdose of the drug.Therefore, it is possible to monitor an actual dose of drug by theelectronic circuit as well as to monitor a dose of drug by the programfor setting the dose in advance, and injection of overdose or underdoseof the drug can be prevented by forced stoppage or the like even when aprogram is operated abnormally, thereby reducing mental and physicalpains caused by use of the motor-operated administration apparatus.

According to a twenty-seventh aspect of the present invention, in theadministration apparatus for medical use according to the twenty-sixthaspect, the comparison detection circuit stops the piston rod when itdetects overdose of the drug, thereby to stop administration. Therefore,it is possible to prevent overdose of drug even when a program isabnormally operated, reducing mental and physical pains caused by use ofthe motor-operated administration apparatus for medical use.

According to a twenty-eighth aspect of the present invention, in theadministration apparatus for medical use according to the twenty-sixthaspect, the dose detection circuit detects the dose on basis of anamount of movement of the piston rod. Therefore, an actual dose of drugcan be detected by the electronic circuit.

According to a twenty-ninth aspect of the present invention, in theadministration apparatus for medical use according to the twenty-sixthaspect, the dose detection circuit detects the dose on basis of a timewhen the piston rod moves at a constant speed. Therefore, an actual doseof drug can be detected by the electronic circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an entirety of anadministration apparatus for medical use according to a first embodimentof the present invention.

FIG. 2 is a diagram illustrating a part of the administration apparatusin the vicinity of a needle holder, for explaining replacement of drugcartridges.

FIG. 3 is a diagram illustrating a state where the needle holder isdrawn from a body of the administration apparatus, for explainingreplacement of drug cartridges.

FIG. 4 is a diagram illustrating a state where the drug cartridge isdetached from the body, for explaining replacement of drug cartridges.

FIG. 5 is an enlarge view of a main part of the needle holder in theadministration apparatus for medical use.

FIG. 6 is an enlarge view of a main part of the needle holder forexplaining operation of the needle holder.

FIG. 7 is a diagram illustrating a state where the needle holder isslid, for explaining operation of the needle holder.

FIG. 8 is a diagram illustrating a piston rod assembly of theadministration apparatus for medical use.

FIG. 9 is a diagram for explaining a state of a detection lever whenattaching a needle assembly onto the needle holder of the administrationapparatus.

FIG. 10 is a diagram illustrating construction of a part of theadministration apparatus in the vicinity of a rear end of the drugcartridge.

FIG. 11 is a diagram illustrating construction of a main part of apiston rod assembly of an administration apparatus for medical useaccording to a second embodiment of the present invention.

FIG. 12 is a diagram illustrating a state where the piston rod assemblyof the administration apparatus according to the second embodiment ishoused in a piston rod holding member.

FIG. 13 is a diagram for explaining operation of the piston rod assemblyof the administration apparatus according to the second embodiment.

FIG. 14 is a diagram for explaining operation of the piston rod assemblyof the administration apparatus according to the second embodiment.

FIG. 15 is a cross-sectional view for explaining engagements of a bushshaft and respective piston rods of the administration apparatusaccording to the first embodiment.

FIG. 16 is a perspective view illustrating internal structure of anadministration apparatus for medical use according to a third embodimentof the present invention.

FIG. 17 is a perspective view illustrating an external appearance of theadministration apparatus according to the third embodiment.

FIG. 18 is a block diagram for explaining connections of components inthe administration apparatus according to the third embodiment as anelectric circuit.

FIG. 19 is a flowchart for explaining operation of the administrationapparatus according to the third embodiment.

FIG. 20 is a flow chart for explaining an administration apparatus formedical use according to a fourth embodiment of the present invention.

FIG. 21 is a block diagram for explaining connections of components inan administration apparatus for medical use according to a fifthembodiment of the present invention as an electric circuit.

FIG. 22 is a flow chart for explaining operation of the administrationapparatus according to the fifth embodiment.

FIG. 23 is a block diagram for explaining connections of components inan administration apparatus for medical use according to a sixthembodiment as an electric circuit.

FIG. 24 is a diagram illustrating construction of a conventionaladministration apparatus for medical use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 1 is a diagram illustrating an entire construction of anadministration apparatus for medical use according to a first embodimentof the present invention.

In FIG. 1, reference numeral 1 denotes an administration apparatushaving, at an end thereof, a target-region contact cover 7 to be appliedto a target region of a patient's body to be subjected to injection whenthe patient performs administration by himself, and a needle assembly 6is housed in the cover 7.

Further, a drug cartridge containing a drug, an end of which is closedwith a plunger (not shown), is inserted in the administration apparatus.When the needle assembly 6 pierces the target region, a piston rod (notshown) that presses the plunger moves, whereby the drug emitted from anend of the drug cartridge is injected into the patient's body.

When the patient replaces the drug cartridge, the target-region contactcover 7 is slid in a direction of arrow A as shown in FIG. 2, wherebythe needle assembly 6 attached to a needle holder 4 is exposed. Usually,cartridge replacement should be performed after a protection cover (notshown) is put on the needle assembly 6 to avoid an accident of errorinsertion of the needle assembly 6. However, description of theprotection cover is omitted.

Next, as shown in FIG. 3, the needle holder 4 is slid in a direction ofarrow B. The needle holder 4 is moved up to a predetermined position,and then the needle holder 4 is swung about a shaft (not shown), wherebythe drug cartridge 2 is exposed from the administration apparatus 1.Thereafter, the patient detaches the drug cartridge 2.

An outline of cartridge replacement is as described above. Hereinafterit will be described in more detail using FIGS. 5 to 7.

In FIG. 5, support struts 9 are provided on both sides of a front end ofthe cartridge holder 3 which holds the drug cartridge 2. Further, theneedle holder 4 to which the needle assembly 6 is attached has grooves 8for slide-guiding the support struts 9, and the needle holder 4 and thecartridge holder 3 are joined to each other by respective grooves 8 andsupport struts 9.

When the patient replaces the drug cartridge 2, as shown in FIG. 6, thetarget-portion contact cover 7 (refer to FIG. 2) is moved up to apredetermined position, and the needle holder 4 is slid in the directionof arrow B until a rear portion of the groove 8 contacts support strut9. When the needle holder 4 reaches the predetermined position, theneedle holder 4 swings about the support strut 9 as shown in FIG. 7, anda front end 2 a of the drug cartridge 2 is exposed at the front end ofthe cartridge holder 3.

Thereafter, replacement of the drug cartridge 2 can be performed. Aftera new drug cartridge 2 is attached, the administration apparatus 1 isset in an injection-ready state by performing a reverse of theabove-mentioned operation.

Further, during injection, only the needle portion of the needleassembly is exposed out of the contact cover. Therefore, at all othertimes, a periphery of the needle holder is covered, thereby preventingan accident such as needle insertion by mistake.

Further, a device for detecting a position of the contact cover may beprovided to prevent an accident such as needle insertion by mistakeduring use. To be specific, the contact cover is detected by a positiondetection device that is provided in the administration apparatus whenthe contact cover is in a used position.

Next, a drug cartridge holding state will be described with reference toFIGS. 8 to 10.

A detection lever 18 is attached to the needle holder 4. FIG. 9 shows astate of the detection lever 18 in a case where the needle assembly 6 isattached to the needle holder 4 (refer to FIG. 8). When the needleassembly 6 is attached to the needle holder 4, a rear end portion of theneedle assembly 6 presses the detection lever 18, and a rear end portionof the detection lever 18 presses the front end portion 2 a of the drugcartridge 2. Further, as shown in FIG. 10, a rear end portion 2 b of thedrug cartridge 2 is pressed by a press member 19 that is slidablyattached to a periphery of a piston rod hold member 16.

The press member 19 comprises a spring member 20 and a stopper member21.

In the above-mentioned construction, presence/absence of the needleassembly 6 and the drug cartridge 2 can be detected by detecting aposition of the press member 19.

Further, when replacing the drug cartridge, the needle holder 4 is movedin a direction in which the needle assembly 6 is attached, by thedetection lever 18 and the piston rod holding member 16, whereby thepiston rod is moved back to an initial position. Thus, operabilityduring cartridge replacement is improved.

As described above, in the first embodiment of the present invention,since the front end of the drug cartridge 2 is exposed by drawing theneedle holder 4 from a body of the administration apparatus 1 andswinging the holder 4, the drug cartridge 2 is detachable with thecartridge holder 3 being held by the administration apparatus 1.Therefore, in contrast to the conventional administration apparatus, thepatient is free from a burden that the patient must separate thecartridge holder from the administration apparatus body every time thepatient replaces the cartridge. Further, the patient can arbitrarilyperform replacement of the drug cartridge regardless of a needleassembly attachment state, thereby facilitating handling.

The administration apparatus for medical use according to the presentinvention is applicable to both of a hand operated administrationapparatus and a motor-operated administration apparatus.

Embodiment 2

Next, an administration apparatus for medical use according to a secondembodiment of the present invention will be described. FIG. 11 is adiagram illustrating a piston rod assembly of a motor-operatedadministration apparatus for medical use according to the secondembodiment of the present invention. As shown in FIG. 11, a bush shaft11 having a length approximately equal to an entire length of the rodassembly and having a male thread (not shown) on its periphery is pushedinto a driving gear 10 for transferring a driving power from a motor orthe like (not shown). Further, a hollow piston rod 12 having, on itsinner periphery, a female thread (not shown) that is screwed with themale thread of the bush shaft 11 has a male thread (not shown) on itsperiphery. Furthermore, a piston rod 14 having, on its inner periphery,a female thread (not shown) that is screwed with the piston rod 12 isscrewed with the piston rod 12. How the bush shaft 11, the piston rod12, and the piston rod 14 are screwed is shown in FIG. 15.

Further, the piston rod 12 and the piston rod 14 are provided withconvex-shaped rotation prevention parts 13 and 15, respectively.Further, as shown in FIG. 12, the piston rod 14 is covered with a hollowpiston rod holding member 16 that allows the piston rod 14 to slidesmoothly. Further, a concave-shaped piston rod rotation prevention part17 which contacts the rotation prevention parts 13 and 15 of the pistonrod 12 and the piston rod 14 to prevent the piston rods 12 and 14 fromrotating, respectively, is provided in the piston rod holding member 16.

Next, actual operation will be described with reference to FIGS. 12 to14. First of all, FIG. 12 shows an initial state, wherein the rotationprevention part 13 of the piston rod 12 is positioned outside the pistonrod holding member 16. A driving force of the driving gear 10 istransferred to the bush shaft 11 and the piston rod 12, and the drivinggear 10, the bush shaft 11, and the piston rod 12 rotate in onedirection in synchronization with each other.

Further, since the rotation prevention part 15 of the piston rod 14cannot rotate because it contacts the piston rod rotation preventionpart 17 of the piston rod holding member 16, a rotational forcetransferred from the piston rod 12 to the piston rod 14 is convertedinto a driving force for moving the piston rod 14 forward, whereby thepiston rod 14 slides in a direction of arrow A as shown in FIG. 13. Themale thread on the periphery of the piston rod 12 is not formed over itsentire length, but a portion of a few millimeters from an opposite sideof the rotation prevention part 13 is an imperfect thread portion.Accordingly, rotation of the piston rod 12 stops when an imperfectthread of the piston rod 12 reaches the thread of the piston rod 14.

Since the rotation prevention part 15 of the piston rod 14 stillcontacts the piston rod rotation prevention part 17 of the piston rodholding member 16, the piston rod 12 that has stopped rotation slides inthe direction of arrow A in synchronization with the piston rod 14.Further, an instant when the rotation prevention part 15 of the pistonrod 14 is apart from the piston rod rotation prevention part 17 of thepiston holding member 16, the rotation prevention part 13 of the pistonrod 12 contacts the piston rotation prevention part 17 of the pistonholding member 16, and therefore, the piston rod 14 slides in the drugcartridge 2 in synchronization with sliding of the piston rod 12 (referto FIG. 14). Then, the plunger of the drug cartridge 2 is pressed,whereby a drug is drained. The piston rod can be returned to the initialstate by performing a reverse of the above-mentioned processing.

As described above, in the administration apparatus for medical useaccording to the second embodiment, an expansion/compression mechanismof the piston rod assembly is composed of the bush shaft 11, thecylindrical piston rod 12 that is screwed with the bush shaft 11, thecylindrical piston rod 14 that is screwed with the piston rod 12, andthe piston rod holding member 16 that stores these piston rods, wherebymotion of the piston rods is expanded linearly in plural stages to makethe apparatus very compact, resulting in an administration apparatus formedical use having excellent portability.

While in this second embodiment a motor-operated administrationapparatus for medical use has been described, the present invention isnot restricted thereto. For example, a hand-operated administrationapparatus for medical use which manually drives a driving gear 10 usinga spring or the like is also within the scope of the present invention.

Embodiment 3

Next, an administration apparatus for medical use according to a thirdembodiment of the present invention will be described with reference toFIGS. 16 to 19.

FIG. 16 is a perspective view for explaining internal structure of anadministration apparatus for medical use according to the thirdembodiment, FIG. 17 is a perspective view illustrating an externalappearance of the administration apparatus, FIG. 18 is a block diagramfor explaining connections in the administration apparatus as anelectric circuit, and FIG. 19 is a flowchart for explaining operation ofthe administration apparatus.

Initially, FIG. 16 will be described.

FIG. 16 is a diagram illustrating construction of a motor-operatedadministration apparatus for medical use which performs an operation ofadministrating a drug using an electric driving source.

In FIG. 16, a syringe (drug cartridge) 101 filled with a drug is set ina cartridge holder 103 that is attached to a body 102 of the apparatus.

A user holds the body 102 with his hand, presses a contact sensoragainst a region to which the drug should be administered, and pushes anadministration switch 104 that is provided on a side surface of the body102. Then, a needle-insertion motor 105 rotates forward, and thisrotational force propagates to a slide cap 107 through a slide rod 106that is directly connected to the needle-insertion motor 105. Therotational force of the needle-insertion motor 105 is converted into aforce of linear motion by the slide cap 107. The slide cap 107 moves ina direction of the arrow when the needle-insertion motor 105 rotatesforward. A needle-removal sensor is turned off as the slide cap 107starts to move. The slide cap 107 moves by a predetermined amount in thedirection of the arrow. At this time, a needle-insertion sensor 109 isturned on, and rotation of the needle-insertion motor 105 stops.

The slide cap 107 is coupled to an inner frame assembly part 110. Whenthe needle-insertion motor 105 rotates forward, the inner frame assemblypart 110 moves in the direction of the arrow. The inner frame assemblypart 110 is coupled to an injection assembly part 111. The injectionassembly part 111 moves in the direction of the arrow when theneedle-insertion motor 105 rotates forward, and inserts an injectionneedle 112 into a target region.

After this needle-insertion operation, an injector motor 113 rotatesforward, and this rotational force is decelerated by a deceleration gearbox 114 directly connected to the injection motor 113, whereby a gearmain shaft 115 of the deceleration gear box 114 is rotated. A front endof the gear main shaft 115 rotates a primary gear 116. This rotationalforce propagates to a tertiary gear 118 through a secondary gear 117.The tertiary gear 118 is coupled to a primary rod 119. Since the primaryrod 119 is engaged with a secondary rod 120, rotational force of theprimary rod 119 propagates to the secondary rod 120. Since the secondaryrod 120 is engaged with a tertiary rod 121, a rotational force of thesecondary rod 120 propagates to the tertiary rod 121. A rotational forceof the tertiary rod 121 is restricted by a groove that is providedinside the cartridge holder 103, and the tertiary rod 121 moves in thedirection of the arrow. When the tertiary rod 121 moves ahead in thesyringe 101 by a predetermined amount, the secondary rod 120 that hasrotated also pushes the syringe 101. Then, the tertiary rod 121 pushes aplunger in the syringe 101 so that a drug is pushed out of the injectionneedle 112, whereby an injection operation is performed. A dose isadjusted by counting rotations of the injection motor 113 by a rotationsensor 122.

The primary rod 119, the secondary rod 120, and the tertiary rod 121have the same construction as the piston rod assembly described for thefirst embodiment.

After the injection operation, the injection motor 113 rotates backwardto return the secondary rod 120 and the tertiary rod 121 to initialpositions. Thereafter, the needle-insertion motor 105 rotates backwardto move the slide cap 107 in a direction opposed to the arrow. The slidecap 107 is coupled to the inner frame assembly pat 110. When theneedle-insertion motor 105 rotates backward, the inner frame assemblypart 110 rotates in the direction opposed to the arrow. The inner frameassembly part 110 is coupled to the injection assembly part 111.Accordingly, the injection assembly part 111 moves in the directionopposed to the arrow together with the inner frame assembly part 110when the needle-insertion motor 105 rotates backward, whereby theinjection needle 112 is removed from the target region.

When the slide cap 107 returns to an initial position, theneedle-removal sensor 108 is turned on to stop the needle-insertionmotor 105, whereby a needle removal operation is completed.

Next, an external construction of the administration apparatus formedical use according to the present invention will be described withreference to FIG. 17.

In FIG. 17, reference numeral 123 denotes a power source switch forturning power on when using the administration apparatus, and turningpower off after use.

Reference numeral 124 denotes an air releasing switch for starting airreleasing in the syringe or injection needle.

Reference numeral 125 is a setting switch for setting such a dose ofdrug to be injected into a body.

Reference numeral 126 denotes a contact sensor for checking whether ornot the administration apparatus contacts a region to be subjected toadministration.

Reference numeral 127 denotes a display unit for displaying a set doseof drug to be injected into the body, and a condition in theadministration apparatus, for example, an amount of remaining drug.Further, the display unit 127 notifies a user of abnormal operation orthe like.

Reference numeral 128 denotes an injection needle port as an openingthrough which the injection needle passes during needle insertion andneedle removal.

Next, an electrical circuit construction of the administration apparatushaving the constructions shown in FIGS. 16 and 17 will be described withreference to FIG. 18. In FIG. 18, the same reference numerals as thoseshown in FIGS. 16 and 17 denote the same or corresponding parts.

Reference numeral 129 denotes a speaker for notifying a user of an endof operation, abnormal operation, or the like by voice.

Reference numeral 132 denotes an origin point sensor for detecting thatthe piston for injecting the drug in the syringe is positioned in anorigin point.

Reference numeral 131 denotes a motor driver for outputting a signal fordriving the injection motor 113 and the needle-insertion motor 105according to a command from a microprocessor 130.

The microprocessor 130 is a controller which outputs a command foroperating the injection motor 113 or the needle-insertion motor 105 byturning on the air releasing switch 124 or the administration switch 104according to a program.

Next, a sequence of air releasing and drug injection by themicroprocessor 130 of the administration apparatus according to thethird embodiment will be described with reference to the flowchart shownin FIG. 19. When the air releasing switch 124 or the administrationswitch 104 is pressed, the sequence starts (step a1).

Next, it is judged whether or not the air releasing switch 124 ispressed (step a2). When the air releasing switch 124 is pressed, theprocess goes to step a3.

In step a3, the needle-insertion motor 105 is operated at a low speedusing a reduction in driving voltage, or PWM (Pulse Width Modulation)control for changing an ON/OFF ratio of a pulse width of a signal,during a period from when the needle-removal sensor 108 is turned on towhen the needle-insertion sensor 109 is turned on. Next, in step a4, theinjection motor 113 is rotated forward by an amount required for airreleasing, and air releasing is performed by moving the piston rods119˜121.

Next, in step a5, the needle-insertion motor 105 is rotated backward ata low speed to move the injection needle up to a position where theneedle-insertion sensor 109 is on, thereby completing processing (stepa9).

On the other hand, when not the air releasing switch 124 but theadministration switch 104 is pushed in step a2, the process goes to stepa6. In step a6, needle insertion is performed at a high speed to reducepain of a patient associated with needle insertion.

Next, in step a7, the injection motor 113 is operated to inject a setdose of drug.

Next, in step a8, after this injection is ended, the needle-insertionmotor 105 is rotated in a reverse direction at a high speed to move theinjection needle from a position of a needle-insertion state to aposition of a needle-removal state, thereby completing processing (stepa9).

As described above, in the administration apparatus for medical useaccording to the third embodiment, when the air releasing switch 124 ispressed using the plural piston rods 119 to 121, air releasing can beeasily performed by the motor with movements of the piston rods 119 to121. Further, since the injection motor 113 is operated at a low speedduring air releasing, it is possible to reduce a risk of a drug adheredto the injection needle or the like being splattered when the uservisually checks air releasing.

Embodiment 4

Next, an administration apparatus for medical use according to a fourthembodiment of the present invention will be described. Theadministration apparatus according to the fourth embodiment alwaysperforms air releasing of a drug cartridge and/or an injection needlebefore performing drug administration to increase a level of safety ofthe apparatus. A construction of the apparatus according to the fourthembodiment is identical to that described with respect to FIGS. 16 to 18and, therefore, repeated description is not necessary.

Hereinafter, operation of the microprocessor 130 of the administrationapparatus for medical use according to the fourth embodiment will bedescribed with reference to FIG. 20.

When air releasing switch 124 or administration switch 104 is pressed, asequence is started (step b1).

Initially, it is judged whether or not the air releasing switch 124 ispressed (step b2). When a pressed switch is not the air releasing switch124 but the administration switch 104, step b2 is performed again. Whenthe pressed switch is the administration switch 104, sinceadministration is not performed, it is informed to a user that theadministration switch 104 is pressed, using speaker 129 by voice orusing display unit 127, or using both of the speaker 129 and the displaydevice 127.

On the other hand, when the air releasing switch 124 is pressed in stepb2, the process goes to step b3. In step b3, it is judged whether or notcontact sensor 126 is on. Since there is a danger that the needle mightbe inserted into the user by mistake when the contact sensor 126 is on,step b3 is performed again. At this time, since air releasing is notperformed when the contact sensor 126 is on, it is informed to the userthat the contact sensor 126 is on, using the speaker 129 by voice orusing the display device 127, or using both the speaker 129 and thedisplay unit 127.

On the other hand, when the contact sensor 126 is not on in step b3, theprocess goes to step b4. In step b4, injection motor 113 is driven torelease air in syringe 101 or injection needle 112.

Next, the user visually checks whether or not air releasing issatisfactorily performed, and presses the air releasing switch 124 againwhen it is not satisfactorily performed.

When air releasing is performed satisfactorily, the administrationswitch 104 is pressed. In step b5, it is judged which of theadministration switch 104 and the releasing switch 124 is pressed. Whenthe air releasing switch 124 is pressed, the process goes to step b3.When the administration switch 104 is pressed, the process goes to stepb6.

In step b6, it is judged whether or not the contact sensor 126 is on.When the contact sensor 126 is not on, there is a possibility that theadministration apparatus is not in contact with a predetermined targetregion of the user, and therefore, step b3 is performed again. Since noinjection is performed when the contact sensor 126 is not on, it isinformed to the user that the contact sensor 126 is not on, using thespeaker 129 by voice or using the display device 127, or using both thespeaker 129 and the display device 127. When the contact sensor 126 ison, the process goes to step b7.

In step b7, a set dose of drug is injected by driving the injectionmotor 113 to complete processing (step b8).

As described above, according to the fourth embodiment, the injectionoperation by pressing the administration switch 104 is enabled afterdetecting that the air releasing switch 124 is pressed before pressingthe administration switch 104, using plural piston rods 119 to 121.Therefore, air releasing can be performed with reliability before druginjection to reduce a risk of injecting air into a human body, whereby alevel of safety of the apparatus is increased.

Embodiment 5

An administration apparatus according to a fifth embodiment of thepresent invention will be described hereinafter. Since construction ofthe administration apparatus according to the fifth embodiment isidentical to that described with respect to FIGS. 16 to 18, repeateddescription is not necessary.

Hereinafter, an electrical circuit structure of the administrationapparatus according to the fifth embodiment will be described.

FIG. 21 is a block diagram illustrating the construction shown in FIG.18 to which a setting circuit 133, a dose comparison circuit 134, and adose holding circuit 135, which are components peculiar to the fifthembodiment, are added, and the display unit 127 and the speaker 129shown in FIG. 18 are omitted for simplification.

The setting circuit 133 is composed of an electronic circuit capable ofstoring an amount of operation of injection motor 113 which is obtainedby converting an amount of injection outputted from microprocessor 130.

The dose storing circuit 135 is composed of an electronic circuit forstoring doses of drug that have been administered in the past. To bespecific, it stores a latest dose, or plural doses in the past, or anaverage of plural doses in the past.

The dose comparison circuit 134 is composed of an electronic circuit forcomparing a dose that is set by the setting circuit 133 with a dose(doses) that is stored by the dose storing circuit 135.

Next, operation of the microprocessor 130 of the administrationapparatus according to the fifth embodiment will be described withreference to FIG. 22.

When a user stands ready to set a dose, a sequence starts (step c1).

Initially, in step c2, a range of dose is calculated from the past setvalues that are stored in the dose holding circuit 135. The range ofdose according to the past set values may be a range from −30% to +30%of the last dose, or a range that is obtained on basis of plural dosesin the past. For example, using an average of data of past ten doses, arange from −30% to +30% of the average value is set as a range of dose.Moreover, a range of dose may be obtained by statistically calculatingdata of past ten doses using standard deviation or the like.

Next, in step c3, the user determines an amount of injection and setsthe amount in the setting circuit 133.

Subsequently, in step c4, the dose comparison circuit 134 compares thevalue inputted by the user in step c3 with a value calculated in stepc2. When a result of this comparison is within a predetermined range,the process goes to step c6. When the result of this comparison is outof the predetermined range, the process goes to step c5 to be describedlater.

In step c5, it is informed to the user that the set value is out of thepredetermined range, using the speaker 129 by voice or using the displayunit 127, or using both the speaker 129 and the display unit 127. Then,the user judges whether or not the process can be shifted to aninjection step. When the user permits shifting to the injection step,the process goes to step c7. When the user refuses, the process goesback to step c3.

In step c6, injection of the set dose is performed by driving theinjection motor 113 to complete the process (step c7).

In step c5, after informing the user that the set value is out of thepredetermined range using the speaker 129 by voice or the display unit127 or using both the speaker 129 and the display unit 127, the processmay go to step c3 without confirmation by the user.

As described above, in the administration apparatus for medical useaccording to the fifth embodiment, when setting a dose using the settingswitch 125, the set value is compared with past doses. When the resultof this comparison is out of a predetermined range, it is informed tothe user using the speaker 129 by voice or using the display unit 127,or using both the speaker 129 and the display unit 127. Depending ontypes of drugs, some drug might adversely affect a human body if a doseof the drug is significantly different from a proper dose. Therefore,when the dose changes significantly, a change of the dose is informed tothe user before administration and then the user confirms the dose, orthe user is inhibited to perform administration, whereby a level ofsafety of the motor-operated administration apparatus for medical use isincreased.

Embodiment 6

Next, an administration apparatus for medical use according to a sixthembodiment of the present invention will be described. Sinceconstruction of the administration apparatus according to the sixthembodiment is identical to that described with respect to FIGS. 16 to18, repeated description is not necessary.

An electrical circuit structure of the administration apparatusaccording to the sixth embodiment will be described with reference to ablock diagram shown in FIG. 23. In FIG. 23, the construction shown inFIG. 18 further includes a setting circuit 133, a comparison detectioncircuit 136, and a count circuit 137 which are components peculiar tothe sixth embodiment, and the display unit 127 and the speaker 129 shownin FIG. 18 are omitted for simplification.

Rotation sensor 122 is able to output operation of injection motor 113as a frequency, and the frequency is output to microprocessor 130 andthe count circuit 137.

The count circuit 137 is composed of an electronic circuit for countingsignals from the rotation sensor 122, and it is able to count an amountof operation of the injection motor 113.

The setting circuit 133 is composed of an electronic circuit which isable to hold an amount of operation that is obtained by converting anamount of injection outputted from the microprocessor 130. Further, thesetting circuit 133 is able to receive an instruction of an injectionstart or an injection end from the microprocessor 130, whereby it canmake the count circuit 137 perform initialization.

A dose can be detected by measuring an amount of movement of the pistonrod or measuring a time when the piston rod moves at a constant speed.

The comparison detection circuit 136 is composed of an electroniccircuit for comparing a set value of the setting circuit 133 with acount value of the count circuit 137 to detect overdose or underdose ofa drug. When the count value exceeds a predetermined value with respectto the set value before end of an operation, the comparison detectioncircuit 136 can stop operation of the motor driver 131, bypassing themicroprocessor 130, and it can inform the microprocessor 130 that thepredetermined value is exceeded. Further, when the count value is lowerthan a predetermined value with respect to the set value after the endof operation, the comparison detection circuit 136 can inform themicroprocessor 130 that the count value is lower than the predeterminedvalue.

In the above-mentioned construction, it is possible to directly observean actual dose electronic-circuit-wise by the comparison detectioncircuit 136, in addition to observing a dose by program processing usingthe microprocessor 130. Therefore, even when a program of themicroprocessor 130 is operated abnormally, the comparison detectioncircuit 136 detects an abnormal event to perform a process such ascompulsory stopping of the motor driver 131, whereby overdose orunderdose of drug can be avoided. As a result, double safeguards can bepresented, whereby a level of safety of the motor-operatedadministration apparatus for medical use can be increased.

The administration apparatus for medical use according to the presentinvention is useful as a motor-operated injection apparatus or the likefor a drug such as insulin, which provides easy replacement of drugcartridges and high portability.

What is claimed is:
 1. An administration apparatus for medical use whichperforms administration of a drug, said apparatus comprising: a drugcartridge having an end closed with a plunger, and containing a druginside; a cartridge holder for housing the drug cartridge; a piston rodfor pressing the plunger in the drug cartridge to move the plunger; aninjector motor which moves the piston rod; a motor driver which drivesthe injector motor; a controller which controls the motor driver tocontrol movement of the injection motor; a needle assembly foradministering the drug emitted from the other end of the drug cartridgewith movement of the piston rod; and an air releasing switch forstarting an air releasing operation for releasing air in the drugcartridge and the needle assembly, wherein the controller performs theair releasing operation with the movement of the piston rod when thecontroller detects that the air releasing switch is pressed, and duringthe air releasing operation, the piston rod is moved at a speed lowerthan a speed of the piston rod during the drug administration operation.2. The administration apparatus for medical use as defined in claim 1,wherein the low-speed operation of the piston rod during the airreleasing operation is performed by PWM (Pulse Width Modulation) controlwith an ON-OFF ratio of a pulse width being varied.
 3. Theadministration apparatus for medical use as defined in claim 1, whereinthe low-speed operation of the piston rod during the air releasingoperation is performed by voltage control.
 4. The administrationapparatus for medical use as defined in claim 1, wherein the controllerpermits the drug administration operation after detecting that the airreleasing operation is performed before performing the drugadministration operation.
 5. The administration apparatus for medicaluse as defined in claim 1, further includes an administration switch forstarting the drug administration operation for injecting the drug withinthe drug cartridge through the needle assembly after the air releasingoperation, and the controller permits an operation by turn-on of theadministration switch after the air releasing operation.
 6. Theadministration apparatus for medical use as defined in claim 1, furtherincludes a contact sensor for detecting whether or not a portion of theadministration apparatus in the vicinity of the needle assembly contactsa target region, and the controller suppresses the air releasingoperation when the contact sensor detects that the portion of theadministration apparatus contacts the target region.